[To be studied in conjunction with "Instructions for the Training of Divisions for Offensive Action," (O.B./1635, December, 1916) and "Artillery Notes. No. 3.‹Counter-Battery Work" (S.S. 139/3) issued by the General Staff.]

February, 1917.

Organisation and Command.

Artillery in the General Plan of Attack

The Role of the Artillery

Selection of the Front of Attack

Estimate of Guns and Ammunition required

The Artillery Plan.

Scope of the Artillery Plan

Allotment of Artillery

Air Observation

The Preliminary Arrangements.

Reconnaissance

Distribution of Work

Positions

Protection of Positions

Observing Stations

Artillery Command Posts

Communications

Control and Direction of Fire

Trench Bridges

Ammunition Supply

Anti-aircraft Guns

The Preliminary Bombardment.

Object of the Preliminary Bombardment

Fire to Effect Physical and Moral Damage

Destruction of ObstaclesWire-cutting

Destruction of Defences and their Accessories

Fleeting Targets

Accuracy of Fire

Forward Guns

Advance Batteries

Character of the Bombardment

The Bombardment of Rearward Lines

Duration of the Bombardment

The Support of the Attack.

The General Mission of the Artillery

Importance of Concealing the Hour of the Assault

Barrages

Object of the Barrage

The Field Artillery Barrage

Strength of Field Artillery Barrages

The Organisation of the Barrage

Pace of the Barrage

Time Tables

Control of the Barrage

Rate of Fire and Depth of Lifts

Enfilade Fire

Ammunition for the Field Artillery Barrage

The Howitzer Bombardment

Consolidation and Counter-attacks

Zone Calls

Information and Communication

The Artillery Advance

Appendix I. Organisation of Artillery Staffs

Appendix II. Diagrams of Barrages [omitted]

Appendix III. Scheme of Work to be undertaken by a Battery to obtain Cover when it has Advanced to a New Position beyond our Old Front Line Trenches [omitted]

Appendix IV. Estimates of Ammunition required

Organisation and Command.

Artillery has so developed both in power and quantity during the past two years that it has become a much stronger weapon of offence than heretofore. To obtain the full value from this arm, which plays so great a part in battle, it is essential that its action should be so efficiently controlled as to ensure that its maximum force is utilised. Every detail regarding the employment of artillery must be thought out beforehand. The efficient execution of its allotted tasks will largely depend on the early issue of clear orders and on the methodical supervision of its subsequent work.

A Commander directs and supervises the action of his artillery through the medium of his Artillery Commander, who must be equipped with the authority, information and technical knowledge essential to his position.

The Artillery Commander attached to the Staff of an Army or a Corps may, within the discretion of his Chief, command the whole of the artillery of the formation; in order that the Commander's plan may, as far as the artillery is concerned, be translated into orders and be carried out in the most effective manner and with the least delay. The rapid transmission of orders to batteries is a matter of vital importance.

The Army deals with the distribution and employment of the artillery allotted to it, and with the details of artillery co-operation with Armies on either flank. It provides for co-operation between the various Corps and decides, within the limitations imposed by the Commander-in-Chief, the nature and duration of the preliminary bombardment.

The Army is also concerned with the general direction of the preparatory arrangements; lays down the general principles to be followed as regards the employment of anti-aircraft guns, counter-battery work, night firing, enfilade fire and concentrations of fire; and indicates the most effective methods to employ in the attack.

A Corps Commander disposes of every nature of artillery essential to the preparation and execution of an offensive operation. There can, therefore, be but one Commander for all the artillery of the Corps, both Field and Heavy, if the energy of the whole is to be sys-tematically and uniformly directed. At the same time, the Army Commander may decide to retain certain units of Heavy Artillery under Army control, and, in many cases, will at least lay down the special objectives to be engaged by the long range big guns (6-inch, 9.2-inch and 12-inch).

A table showing the details of organisation of Artillery com-mands is given in Appendix I.

This new organisation recognises the great importance of recon-naissance work on the part of the artillery, and each Artillery Staff is provided with an officer charged with the execution of such work. The study and collation of information derived from air photo-graphs and maps, as far as it affects the artillery, form an important feature of the officer's duties.

The organisation of the Staff of the Corps Heavy Artillery Com-mander is designed to meet the double task that falls on his shoulders. Broadly speaking, destruction of defences and of communications, combined with barrage work, comprise the one branch of Heavy Artillery work; Counter-battery work the other. It is, however, essential that no hard and fast line shall be drawn between these two main sub-divisions of the Heavy Artillery Commander's duties. Organisation must be so supple as to ensure that at all times it shall be a simple matter to devote any proportion of the Heavy Artillery to either task, according to the needs of the tactical situation, without delay and without confusion. Arrangements must be made to ensure that Heavy Artillery Groups engaged on trench bombardment are in a position to co-operate closely with the Divisions interested in the hostile trenches in question.

Army Field Artillery Brigades have been formed to provide a means whereby a mass of field artillery may be concentrated for any special purpose. Such brigades can be allotted to Armies, Corps and Divisions as circumstances may require.

Despite this new organisation, a Division in the early stages of an offensive operation will often require for its support more field artillery than is afforded by its own Divisional Artillery; even though reinforced by such Army F.A. Brigades as may be allotted to it. In this event, two or even three Divisional Artilleries may be found supporting the operations of a single Division. In such cases all this field artillery will normally be grouped under the C.R.A. of the attacking Division.

The composition of heavy artillery groups may, as explained in "Artillery Notes, No. 3" (Counter-Battery Work), consist of both gun and howitzer batteries, or of either nature separately; so long as the action of all the batteries devoted to any one area is controlled by one authority. One point, however, must always be borne in mind, and that is that the composition of Heavy Artillery Groups must envisage the demands of an early advance. Mixed groups of medium and heavy weapons present the obvious disadvantage that in the event of a rapid advance, either the medium batteries (which will be the first to advance) must break loose from their groups, or fresh groups must be automatically formed to control the advancing batteries.

The relations between the Artillery and the Royal Flying Corps must be of the closest if these two arms are to work together effectively to the common good.

This particularly applies to the case of counter-battery work, as is impressed in the "Artillery Notes" (No. 3) dealing with that subject.
G.Os.C., R.A., of Armies (or Corps) deal direct with the Com-manders of Corps and Balloon Wings (or Squadron and Balloon Companies) in all matters relating to their combined work, and should do all in their power to impress upon their subordinates the value resulting from mutual confidence based upon mutual under-standing. The Corps and Balloon Wing Commanders are, however, the executive commanders of the Corps Squadrons and Balloon Companies respectively and as such act as the technical advisers of G.Os.C. R.A. of Corps, with whom they should be in the closest touch.

II. Artillery in the General Plan of Attack.

The Role of the Artillery.

The rupture of the enemy's front, generally strongly defended and organised in depth, is the first phase of an offensive battle.

This entails the destruction of the obstacles to the infantry's advance and of the means of defence that support those obstacles; the moral and physical reduction of the defenders; and lastly a rapid and combined advance of all arms acting in close co-operation.

Thereafter successive phases may comprise a modified form of the first; namely the attack of improvised lines of defence with but little time for deliberate preparation, leading to a final phase of open warfare.

Experience has proved that effective artillery preparation is in-dispensable to success, the extent and nature of the preparation depending on the scope of the intended operation. In each sub-sequent phase the artillery must aim at maintaining the closest touch with, and affording the greatest support to the infantry. The measure of ultimate advantage will largely depend on the momentum of the first blow, and the rapid exploitation of early successes before the enemy has time to recover from the shock.

Selection of the Front of Attack.

Granted the vital importance of effective artillery action in the offensive, it follows that the general plan of attack must be such as to admit of a full development of artillery fire and of complete co-operation between the artillery and the infantry.

For this it is not enough that the requirements in guns and ammunition should have been carefully estimated and adequately provided. The first and most essential element of success is that the front selected for attack should be of a nature to admit of this full development and co-operation. Conditions are most favourable when the ground allows of artillery commanders

seeing clearly the enemy's defences, and also following the
movements of the attacking infantry;

controlling the fire of their guns rapidly and effectively. For, however carefully thought out the arrangements for the control of both artillery fire and infantry movement may be, they are always liable to be thrown out of gear by some unexpected development.

It is, then, the first duty of the artillery commander to place before the general officer commanding the force full particulars as to the manner in which the ground affects the efficiency of the artil-lery preparation and support, so that the latter may give due weight to such considerations in selecting the front of attack. "An objec-tive which may appear at first sight easy of access to the infantry, may prove in the end costly to attack, if it does not lend itself to the judicious application of artillery fire; and vice versa, localities which present difficulties to the infantry alone may, if it is possible to bring the converging fire of artillery to bear on them, be carried with comparatively little loss."

Estimate of Guns and Ammunition Required.

The general plan of attack having been settled, it is the next duty of the artillery commander to prepare an estimate of the amount of artillery and of ammunition required for the operation.

The first point to remember is that the ammunition required depends upon the work to be done, more than on the number of guns available. The latter is, however, the governing factor as regards the time which will be required for the preparation, and has therefore an important bearing on the general plan of attack. If surprise forms any part of this plan, it is essential that sufficient fire units should be available to allow the different portions of the enemy's defences to be bombarded simultaneously. The number of hostile batteries to be dealt with is another consideration directly affecting the amount of artillery that will be necessary.

The nature of guns required depends, like the ammunition, on the character of the work to be performed. Every type of gun or howitzer is particularly adapted for certain tasks, and the pro-portion of each type demanded should be based on such considerations.

An estimate of the guns and ammunition needed can, there-fore, only be made after thorough reconnaissance of the enemy's system of defence; including his trenches, machine-gun emplacements, observing stations, communication trenches, rear lines, strong points, wire, &c. This reconnaissance must include not only the examina-tion of the ground from all possible points of view, but also the reports of air observers, and a very careful study of maps, air photographs, and of all information available in the intelligence section. This section should indicate the roads used by the enemy in bringing up reinforcements and supplies of ammunition and food, the places where they can best be blocked by artillery fire, and the forming-up places likely to be used for counter-attack. The number and nature of the guns which may be brought into play by the enemy is also an important factor, as it governs the requirements for counter-battery work.*

It is important that the Artillery Commander should make this reconnaissance in company with the General Staff of the formation, and that the fullest information, regarding not only the enemy's defences but also his habits, should be obtained from both the artillery and the infantry holding the front.
[* Counter-battery Work has been dealt with in a separate note (No. 3 of this series).]

III. The Artillery Plan. **

Scope of the Artillery Plan.

In all offensive operations it is the duty of the Artillery Com-mander of the force engaged to prepare an artillery plan, based on and supplementary to the general plan of attack.

To enable him to do this he should be informed as early as possible of the minimum resources of guns and ammunition that will be available.

The plan should consist of a clear and complete statement of the objects to be attained by the artillery and the methods to be employed. It will lay down the allotment, grouping and organisation of the artillery (including medium and heavy trench mortars) for the attack; the tasks and zones of the various commands; and the arrangements for observation, communication and the co-operation of aeroplanes and balloons. It will deal with the establishment of artillery command posts, the expenditure and supply of ammunition, arrangements for liaison with the infantry, the forward movement of batteries, and any other points regarding the action of the artillery which it is necessary to include. The measures to ensure co-operation between subordinate formations and the possibility of bringing a heavy concentration of fire on to particular areas, if required, must be thought out and clearly defined. The preparation of this plan will thus involve a compre-hensive consideration of all the tasks which the artillery will or may be called upon to perform during the preparation and execution of the attack.

The plan must embrace each phase of the battle, and careful arrangements must be made to ensure that one phase shall follow another without any unintended break in the action of the artillery.

The lower the formation concerned, the more detailed will be both its artillery plan and the study and reconnaissance upon which that plan is constructed.
As soon as the broad outline of the artillery plan has been worked out and approved, it is advantageous to issue it to subordinate commanders concerned, or at least to make it known to them at a conference; in order that they may have the earliest opportunity of studying and solving their individual problems. Even if cir-cumstances ultimately entail modifications in the sub-allotment of artillery and in the apportionment of tasks, the inconvenience arising from minor changes in subordinate plans is far outweighed by the advantage gained by the increased time thus rendered avail-able for consideration of the general tasks demanded and for recon-naissance. To complete the manifold arrangements essential to the successful execution of an artillery plan is necessarily a lengthy process. The early publication of the plan, even if not in all its details, will greatly assist the work of subordinate artillery com-manders.
[** See Appendix A., para. 2. of "Instructions for the Training of Divisions for Offensive Action."]

Allotment of Artillery.

The number and variety of the tasks which the artillery is called upon to perform necessitate very careful arrangement, if the different natures are to be employed to the fullest advantage. These tasks depend upon, and must therefore vary with the nature of the enemy's defences and the strength of his artillery. The following principles, however, will generally apply.

Roles of Various Natures of Artillery.

Field guns (18-pdr.) are primarily employed in barrage fire, repelling attacks in the open, raking communications and wire cutting. They may also be employed for neutralizing fire against batteries within their reach, and to assist in the destruction of such enemy defences as are vulnerable to the H.E. shell of field guns, e.g., breastworks and barriers. They will also be required for the purpose of preventing the enemy from repairing damage to his defences, where this work is beyond the power of the infantry.

Medium guns (60-pdrs.) are employed in counter-battery work, especially for neutralization; for raking communications, and form-ing barrages beyond the range of field guns.

Heavy guns (6-inch, 9.2-inch, and 12-inch) are used against villages, camps, dumps, railway stations, &c., beyond the range of other artillery. Also against observing stations, such as chimneys and church towers, and occasionally for long range counter-battery work.

6-inch guns are also used against balloons and for enfilading distant trenches.

Field howitzers (4.5-inch) are employed for the bombardment of the weaker defences; enfilading communication trenches and against troops that are badly entrenched; for destructive counter-battery work against ill-protected batteries and for neutralization with gas shells; for barrage work, especially by night; also (when No. 106 fuze is provided) for cutting wire which is beyond the wire-cutting range of field guns (3,200-3,400 yards), wire at short distances from our own trenches, in hollows, on iron standards and of the "knife-rest" type.

Medium howitzers (6-inch) are used for destruction of defences and against entrenched troops. They are very effective for neutralizing fire against hostile batteries, though not really powerful enough to destroy well constructed emplacements. They are of great value for destructive work in an advance, when the enemy's guns are forced back into positions more or less hastily constructed, and can also be used with No. 106 fuze for barrage fire and for wire-cutting.

Heavy howitzers (8-inch and 9.2-inch); the principal roles of these weapons are counter-battery work against batteries provided with good cover and the destruction of strong defences. They also may be employed for barrage work with No. 106 fuze.

Super heavy howitzers (12-inch and 15-inch) are required for the destruction of specially strong defences, bridges, &c. The 12-inch howitzer is also used with great effect for counter-battery work.

Light trench mortars* may be used to harass the enemy in the final stage of the bombardment, for barrage work and for the close support of the infantry. They are not usually employed during the course of the preliminary bombardment.
Medium trench mortars* are employed to assist other artillery in wire-cutting and in the preliminary bombardment. Owing to their liability to be destroyed by hostile artillery fire it may often be advisable to defer opening fire with these mortars till the last day of bombardment.

Heavy trench mortars* are of value for the destruction of dug-outs and strong points within the limits of their range.

In allotting tasks to guns and howitzers for the preparation of an attack on a large scale, simplicity must be the keynote of the scheme. Heavy howitzers' tasks should preferably be arranged in "lanes" in the same way as are those of field guns. Enfilade fire against the enemy's main system of defence, in the case of all heavy** artillery, should as a general rule only be employed for special reasons (e.g. in the case of a limited offensive or of a marked salient). Guns and howitzers placed for enfilade fire can usually only play a very limited part in the actual attack and, the greater the success, the earlier will they have to change to an entirely new arc of fire. Moreover signal communications are greatly complicated under conditions of enfilade.
[* The handling of Trench Mortars as a whole is dealt with in Artillery Notes No. 6.Trench Mortars.]
[** Enfilade fire from field artillery will often offer great advantages (see para. 12 Section VI.).]

Air Observation

A great deal of artillery work, especially counter-battery work, must depend upon the co-operation of the Royal Flying Corps. It is the duty of the Artillery Commander, in consultation with the Royal Flying Corps Commander concerned, to consider the most suitable allotment of the aeroplanes available, and to include in his artillery plan the arrangements decided upon. A factor which must always be borne in mind is the jambing of wireless. This limits the number of machines which can work on any particular front at the same time. One machine to every thousand yards may be taken as a maximum.

Pilots and observers allotted to artillery work should, in principle, work with the same units throughout both the preparation and the battle itself, and should be changed as seldom as possible. Close personal touch between pilots and observers and the battery commanders for whom they work is of the first importance.

Balloon companies are allotted to Corps for artillery work and must work in close touch with the Corps Squadron. The selection of suitable targets for the aeroplanes and balloons is the duty of the artillery commander, who should make a point of seeing his Corps Squadron and Balloon Company Commander together every evening to decide the allotment for the ensuing day. An intimate knowledge of the country is the chief essential of successful balloon observation. Balloons should, therefore, be changed from one area to another as seldom as possible.

The principles governing the work of aeroplanes and balloons for the artillery are explained fully in "Co-operation of Aircraft with Artillery" issued by the General Staff, December, 1916 (S.S. 131).

IV. The Preliminary Arrangements

Reconnaissance

Thorough reconnaissance of the enemy's defences and dispositions, and also of the ground available, is the first step in the work of preparation. With this object it is of the greatest importance that the various artillery commanders should get into touch as soon as possible with the commanders of the infantry whose attacks they are to support. Equally must they establish an early understanding with the R.E., Signals and R.F.C officers on whose assistance they rely.

Maps or diagrams require to be prepared showing the artillery tasks in detail, wire to be cut, defences to be demolished, routes to be employed by artillery in movement, signal communications, allotment of O.Ps. charts of visibility from O.Ps., and arcs of fire or other means of showing the quantity and nature of fire that can be brought to bear on any given point.

Many of the necessary reconnaissances must be made in conjunc-tion with the infantry or other officers directly concerned with each particular problem; in that time may be saved by all arms and branches working in close co-operation from the first. Infantry officers should examine the ground from artillery observing stations, artillery officers from the trenches and from balloons and aeroplanes, while combined reconnaissances from the ground or from the air must be completed by joint study of aeroplane photographs and maps.

By these means not only should no point for consideration be over-looked, but each arm will learn to appreciate the capabilities and limitations of the others.

Distribution of Work.

A thorough understanding of the work to be done, and of the time at which it is to be done, is essential to the success of the artillery preparation and subsequent action. The work must first be divided amongst the subordinate artillery commands, e.g., in the case of a corps between the different divisional artilleries and the heavy artillery. Subordinate commanders then allot tasks and zones to their brigades and groups and the commanders of these to their batteries.

Positions.

Positions will have to be found for the large number of extra guns, howitzers and trench mortars which will be required for an offensive operation of any size; as well as probably for several of those already in action whose original positions were selected with a view to defence.

The artillery must aim at extending its destructive action over as deep a zone as possible, and at being able to engage the enemy's most distant batteries.
These considerations and the importance of reducing movements of guns to a minimum during the earlier stages of a battle demand that a large proportion of the attacking artillery shall be placed well forward.

What this proportion should actually be will depend chiefly on the range to the various objectives, the ground, the facilities for ammunition supply and the characteristics of the material. It is a mistake to mass a great number of batteries within too confined an area (particularly a valley), where they may all be neutralised at the same time by a comparatively few hostile guns or by a gas attack.

It may sometimes be necessary for corps and divisions to place their batteries outside their own area. Whenever this is the case the necessary arrangements should be made by the next higher formation; but it is to be remembered that the placing of a battery outside the area of its own formation nearly always entails certain difficulties as regards signal communications, ammunition supply and subsequent advance. This procedure, therefore, is not to be recommended unless distinct tactical advantage is thereby gained.

Protection of Positions.

The procedure of withdrawing the detachments from a battery which is being shelled is incompatible with the preparation and support of an infantry attack, when the guns must be fought regardless of the enemy's fire. In principle, therefore, every field and medium battery should, as far as possible, be provided with cover strong enough to resist bombardment by the enemy's heavy field howitzers (5.9-inch).

Considerations of labour and material may, however, prove to be limiting factors, and in this case a careful system of concealment (camouflage) must be adopted for such batteries as are not otherwise protected. Even so, it is essential that shell-proof cover should be provided for the detachments close to the guns. The battery com-mand post must always be strongly protected. Large reinforcements of artillery will usually arrive within a week or two of the opening of the preliminary bombardment, and their actual positions, telephone communications, approaches, and ammunition dumps must be well on the way towards readiness, as these matters are essential to con-trol, direction, and delivery of fire. In order that on arrival these batteries may waste no time in preparing their positions, large dumps of R.E. material should be made at convenient points at an early date. Tables should be prepared, showing the average amount of material required to dig in a battery of each calibre, so that indenting may be simplified and a battery be able to draw its materials and to begin work without delay. When batteries move forward there will be a great demand for protective material, and this fact must be borne in mind when allotting resources.

Apart from the question of the strength of the cover provided, the concealment of emplacements should always be studied during their actual construction. As soon as work starts, either camouflaged screens or rabbit-netting threaded with grass, &c., can be erected on short stakes over the area to be excavated while the personnel work underneath. In this connection it must be remembered that, during the preparation for an offensive on a large scale, the difficulty of concealing guns and tracks leading to them will be greatly lessened by the fact that the ground, within about three miles of the trenches, will be broken up in every direction by numerous other constructional works.

Guns concealed in the neighbourhood of ruined villages, rubble-heaps, brick-stacks, and so on, are particularly difficult of location from the air.
Field Artillery ammunition should always be strongly protected against hostile artillery fire, while the cartridges of heavier natures should be similarly treated, even if it is not possible to do the same for the shells.

Observing Stations.

The provision of a sufficient number of strongly constructed observ-ing stations and of covered approaches to them is a matter of vital importance. To risk the interruption at critical moments of the whole system of directing artillery fire for want of energy in this matter is inexcusable. Telephonists' dug-outs and exchanges must be made practically impervious to artillery fire. All work of this nature must be treated as a matter for continuous attention, and must never be left to the eve of an offensive. Corps must arrange for considerable assistance by Royal Engineers in this work which cannot be effectively executed by gunners alone. Every part of the hostile lines should be visible from at least one O.P.

The allotment of O.P.'s is a matter calling for the direct inter-vention of Corps Artillery Commanders. All Artillery headquarters, from Corps downwards, should possess a chart showing what can be seen of the enemy's defences and territory from each O.P. under their control, and also a photograph of the view from each. Armed with this information it is the duty of the Corps Artillery Commander to allot observing stations to the Artillery of the Corps, so that the best value is obtained from them. O.P.'s will usually be allotted to certain batteries, at least as regards maintenance and control; but it will often occur with large concentrations of artillery that any one O.P. may have to serve two or even more batteries.

The establishment of special Artillery Observing Stations for watch-ing the progress of the infantry and reporting it to Corps Artillery Headquarters has proved to be of great value. The probable future positions of similar stations on the far side of the hostile trenches, should be studied and be made known to the infantry before the assault, so that they may be available for the transmission of infor-mation in general.

Artillery Command Posts.

The selection of Artillery Command Posts (including Brigade and Group Headquarters) is another important matter which must be done by General and R.A. Staffs of Corps in consultation. These command posts should not be changed until the time to advance arrives, when they should be moved to equally permanent positions. They must be so sited that they are likely to be out of constant shell fire, as once communication between Artillery Commanders and their batteries becomes impossible or even difficult, organised operations cease.

Communications.

Previous to an offensive operation it will be necessary to provide the requisite communications for a much larger force of artillery than will normally be engaged in holding the line, and this requires very careful organisation. The actual communications to be estab-lished in each case must depend upon the organisation of the artillery. They will include, in addition to the ordinary framework in the way of command posts and observing stations, the communi-cations required by the higher Artillery Commanders. These latter will be laid by the signal service, but it is essential that such circuits should be kept quite distinct from the general system.

In order to save labour, and at the same time to obtain real effi-ciency in telephonic communications, the whole of the artillery communications in the Corps should be worked out as one plan by the Corps Signals, who must take executive control of all artillery lines. Corps signal schemes must be co-ordinated by Army Signals. An organised system of trunk lines and exchanges in the forward area, supervised by experts, is best calculated to attain the end in view at minimum expenditure of resources. Large infantry working parties for digging in wires will be required both in the preparatory stages and after an advance. This must be taken into consideration when labour requirements are being calculated. It is impossible to take too many precautions to avoid the interruption of communication.

In addition to protecting the telephone wires, as far as this is possible, preparations must be made for the rapid opening of alternative means of communication. Visual signalling is the most important of these, and stations should be selected and estab-lished. Possible points in the enemy's lines should also be selected beforehand, so that, after the attack has succeeded, intermediate observers may know where to look for signals. The establishment of central stations from which messages can be sent on by telephone will prove of great assistance. Short range wireless sets have been successfully used (up to 7,000 yards) where visual signalling is impossible; but in such cases reliance will often have to be placed on orderlies, either on foot or on bicycle. Here, again, arrange-ments must be made in advance so that everyone may know what to do when the time comes.

Control and Direction of Fire.

Accuracy of fire is a matter of the utmost importance. It demands studious attention to calibration of guns, calculations for atmo-spheric and other errors, and to the selection and thorough registra-tion of a few well-chosen Datum Points which must be daily used for checking ranges.

Artillery boards, carefully prepared and kept up to date, are an essential to this system which, particularly in the case of heavy howitzers, is more satisfactory, more economical in ammunition and less likely to disclose the amount of artillery present than was the old system of indiscriminate registration of innumerable points. The latter has proved to be neither necessary nor desirable.

In order, however, to ensure that newly arrived batteries shall be able to register their Datum Points with absolute thoroughness, and that all batteries shall be able to check their ranges two or three times a day on these points (a matter of the utmost importance during the bombardment, and even more so on the day of attack), it is essential that Corps Artillery Commanders shall make detailed arrangements for this work to be carried out, so that confusion of observation shall be avoided.

As already explained, the simpler the artillery fire plan is, the greater the hope of its successful execution. If the ground to be bombarded be divided up into lanes and clearly defined areas, both checking ranges on Datum Points and observation during bom-bardment will be immensely facilitated. Lanes or areas* must be distributed on a time table issued daily by the Corps, so that every hour is fully occupied. Unless every Battery Commander follows a clear system based on these lines, great confusion will inevitably result and the efficacy of the artillery fire will be correspondingly diminished.
[* Areas should be about 500 yards square, each containing a definite target, such as a line of trench, running approximately across the centre.]

Trench Bridges.

The preparation and transport by artillery of portable trench bridges has not been found to be universally necessary. Trenches are crossed more easily and more quickly by the simple process of filling them in. Good strong bridges are, however, required in large numbers for constructing ammunition routes across captured trenches in the event of wet weather, as under such conditions the filled-in places over which guns may have crossed will soon become soft and impassable.

Ammunition Supply.

During the preparatory period the preliminary arrangements in connection with the supply of ammunition are amongst the first matters to be taken in hand, for the Commander's power of manoeuvre is largely dependent on the supply of ammunition. To ensure the smooth working of this supply, careful plans must be made from the commencement.

The construction of railways, light railways and roads for the conveyance of ammunition must be started a long time before operations commence. Roads without railways can ill stand the strain of ammunition traffic. Wherever possible, special roads should be reserved for the use of ammunition lorries and wagons, so that their own movements and the movements of troops may not be blocked. Material for the extension of the light railways should be dumped near their termini, in order that they may be carried for-ward as soon as the advance takes place. It has often been found that the state of the ground after a bombardment makes it impos-sible to supply ammunition, except by pack transport, to those batteries that have advanced. Arrangements must be made before-hand to deal with these conditions if there is any possibility that they will arise.

In order to meet any possible breakdown in the railway or other unforeseen emergency, an Army reserve of ammunition should be made in a central position before the commencement of operations. In excess of their echelons, which must be full, Corps should dump sufficient ammunition for the preliminary bombardment, and for expenditure on the day of attack and the day after the attack. At least 20 per cent. of the ammunition so dumped should be held in Corps reserve. In addition, each battery should dump at its posi-tion sufficient ammunition for its own requirements plus a small reserve, and not according to a fixed scale. All the ammunition should be close to the guns in order to save labour during the strenuous periods of the preliminary bombardment and the day of attack.

Anti-aircraft Guns.

Anti-aircraft Artillery must be disposed during the preparatory period so as to prevent hostile aircraft from reconnoitring and from bombing ammunition dumps, railways, &c. As a general guide, units forming the front line barrage are best sited at about 4,000 yards apart, and at an average distance of 3,000 yards behind the front line trenches. Units required for the second line barrage will generally amount to about half the number of those required for the front line, and should be placed at a distance of about 5,000 yards from them. Anti-aircraft gun posi-tions, once definitely located by the enemy, are unlikely to remain tenable for long. Units should, therefore, change their positions frequently, and this entails the selection and preparation of an adequate number of sites, each of which must be linked up to the Army anti-aircraft telephone system.

V. The Preliminary Bombardment.*

Object of the Preliminary Bombardment.

The task of the Artillery in an offensive battle is to prepare the way for the infantry and to support and protect the infantry throughout its progress. The preparation of the way is achieved by the preliminary bombardment which aims at

the overpowering of the hostile artillery;

the physical and moral reduction of the enemy's infantry;

the destruction of material obstacles to the advance of the attacking infantry and of other defences.

Action against the hostile artillery, a matter of the greatest impor-tance in all operations, is dealt with in detail in G.H.Q. Artillery Notes No. 3Counter-Battery Work, and will only be referred to in this paper in general terms.
[* See Section III, para. 3 of "Instructions for the Training of Divisions for Offensive Action."]

Fire to Effect Physical and Moral Damage.

The enemy will suffer a certain degree of physical and moral loss both from action against his artillery and from the destructive fire directed against his defences. But his power of resistance must be reduced by further special measures. Fire must be directed with the object of denying to the enemy the arrival of reliefs, reinforce-ments, ammunition and supplies of all kinds. Communications, places of assembly, bivouacs, billets, dumps, railway stations, head-quarters, &c., must all be attacked by artillery on a considered and clearly ordered scheme. The share of Field Artillery in this work consists by day chiefly in searching communication trenches (especially trench junctions) between the points bombarded by heavier natures and other approaches that are hidden from view, while by night it will fire on communication trenches, tracks, roads, cooking places, and so on in the forward zone. The heavy artillery should fire by day and by night on roads, railways, billets and other targets beyond the reach of field artillery. The damage to roads effected by the general bombardment has proved to be a serious obstacle to the subsequent advance. This point must be borne in mind when ordering the fire of heavy howitzers on or in the neighbourhood of main roads. The use of instantaneous fuzes in these circumstances may minimise the damage done.

In selecting batteries for these tasks due regard should be paid to the obvious advantage of enfilade fire against communications of all kinds.
Gas shell, if used in sufficient quantity, may give good results against such objectives as ravines and woods; especially at night when fear of them will compel the enemy to wear gas helmets.

The guiding principle of all artillery fire against communica-tions, &c., is to employ short sharp bursts of fire at irregular intervals of time. By day these tasks will not call for the special employment of a large number of pieces. On the contrary batteries of suitable calibre and selected with regard to their position should be detailed to carry out this work in addition to other duties. By night, however, fire of this nature must be much more vigorously conducted in order that the enemy's efforts to relieve or supply his forward troops may only be possible at the cost of heavy casualties and that the moral of his garrisons may derive no benefit from a comparative lull in the artillery fire; indeed a searching shrapnel fire on approaches must be almost continuous. To achieve this without imposing on the artillery too great a burden it is necessary to reserve a certain number of field batteries (gun and howitzer) and of sections of heavy artillery especially for night-firing tasks, or else to organise a system of reliefs of personnel within batteries. Otherwise the artillery will either be tired out before the assault or the night firing will not be conducted with the vigour and care that are so essential. Infantry can co-operate with the artillery against near objectives by means of direct and indirect machine gun fire.

A sound fire scheme of this nature can only be prepared after a detailed study of maps and air photographs, assisted by information gleaned from prisoners. During the bombardment itself, if of any considerable duration, the plan should be constantly reconsidered and modifications introduced, so as to keep the enemy in a state of uncertainty as to our intentions and therefore exposed to loss. This phase of the artillery action is highly important and must never be allowed to become a mere matter of routine. Every round expended on a definite plan, right back to extreme range, is well spent.

Destruction of ObstaclesWire-cutting.

The principal obstacle that has usually to be destroyed is the enemy's wire.
Wire-cutting has been in the past chiefly the "task of the 18-pdrs. and medium trench mortars, and is carried out in each divisional zone by the Field Artillery allotted to that zone, any assistance required from neighbouring Field Artillery units being arranged by the G.O.C. R.A. Corps." The provision of instantaneous and non-delay fuzes for howitzers introduces an entirely new factor into the wire-cutting problem, which it may become possible to solve far more easily and in much less time than has hitherto been the case.

"Wire-cutting demands the closest co-operation between the artil-lery and infantry. Commanders of assaulting battalions should visit the O.P.'s of the batteries cutting the wire on their front to watch the progress of the work, and should inform the battery commanders when they consider that the wire has been properly cut. In addi-tion, patrols should be sent out nightly during wire-cutting to examine and report on the progress made during the day."

"Once gaps have been made, it is the duty of divisional com-manders to employ all means at their disposal to keep these gaps open during the hours of darkness throughout the period of the prepara-tory bombardment. These means include the use of rifle and machine-gun fire, rifle grenades, &c. Much artillery ammunition can thus be saved, and so can be used for strengthening the fire on communi-cation trenches and other approaches."* The amount of artillery fire that is generally available in any offensive battle is now so great that wire, as a factor of defence, tends to lose much of its old importance.
[* See Section III., para. 3, of "" Instructions for the Training of Divisions for Offensive Action."]

Destruction of Defences and their Accessories.

The objectives that are to be destroyed during the preliminary bombardment are stated in the Corps' artillery plan, after the ground, maps, air photographs and all other sources of information have been thoroughly studied. To attempt complete destruction of the enemy's trenches is impracticable, except in the case of enfilade fire, and it is unnecessary. The artillery's task being to open the way for the infantry, its fire must be directed towards breaking down, firstly, the enemy's material powers of resistance and, secondly, his means of directing his defence, incidentally thus increasing his demoralisation by causing casualties and inducing confusion. The enemy's material powers of resistance include such targets as machine-gun emplacements, strong points, important trench junc-tions, selected dug-outs, and other shelters. His signal communi-cations, command posts, observing stations, water-pipe systems, &c., must be shelled with the object of disorganising his defence. As a general principle it is best, particularly in the case of a long bom-bardment, to destroy first those objectives which are most dangerous, or will give the enemy the most trouble to repair.

The extent of the ground to be bombarded will naturally depend upon the objective assigned to the attack. In all cases the enemy's defences for several hundred yards to either flank, the distance depending upon the lie of the ground and the trace of the works, must be dealt with as severely as the front of attack itself; while all salients within 1,200 yards of the front attacked, from which flanking fire could be brought to bear, must receive drastic treatment. The enemy's system of communication (telephone and telegraph) should be broken down at the outset; fire being directed with this object in accordance with the information gleaned from prisoners and air photographs. The object will naturally be best obtained by shelling battle headquarters and telephone exchanges where many wires meet.

Important trench junctions must be destroyed so that reliefs and ration parties, &c. may be compelled to expose themselves to shrapnel fire.

Deep dug-outs present an almost invulnerable target, even to the heaviest artillery; the best result that can be expected is the blowing in of some of the entrances. But such dug-outs, though they afford good protection, should not prove an ultimate salvation to the enemy's infantry, who will be unable to emerge from them in time to meet the assault, if the barrage and the infantry's advance are properly co-ordinated and exactly executed.

Machine guns still remain a formidable asset to the defence. A certain number are housed in concrete emplacements, and these must be destroyed before the assault takes place. The best method of dealing with machine guns which are maintained in deep dug-outs and brought up to the parapet to repel an assault is considered in the paragraphs dealing with the field artillery barrage. Another method frequently employed by the enemy has been to place machine guns in shell holes and other ill-defined positions outside the actual trenches. These, though more commonly met with in the later stages of the battle, may be successfully countered by searching all the ground in front of and behind the immediate objective with shrapnel every day, a procedure calculated to make any shallow position untenable. The "Creeping Barrage" should finally account for any machine gunners that survive.

The destruction of observing stations is dealt with in "Counter-Battery Notes"; they must not be overlooked.

The destruction of trenches and strong points is primarily the task of trench mortars and howitzers of all descriptions, other than the field howitzer which, in future, will have nothing but instan-taneous fuzes and so be chiefly a man-killing weapon. "Guns can, however, be employed with advantage against breastworks, trenches taken in enfilade, barricades, houses and other vertical targets."

"The extent to which the enemy's trenches and works should be destroyed has become a matter for serious consideration."* If they are more or less completely demolished, little or no cover will be left for our infantry. This, though of no moment in the preliminary bombardment of the enemy's front line system of defence before the launching of an attack on a large scale, has been found to prove a grave disadvantage when the trenches gained have to be held; a case that will arise in a limited offensive or in the later stages of a battle aimed at gradually wearing out the enemy's power of resistance.

The bombardment of woods and villages should not consist of an indiscriminate shelling of the whole area. The portions that require bombardment, whether because they are to be captured or because they flank the advance, must be definitely determined.

In all cases it is necessary to arrange to prevent by fire the repair of destroyed or damaged defences. In this, as with cut wire, infantry can assist to a considerable degree.
[* See Section III., para. 3, of "Instructions for the Training of Divisions for Offensive Action."]

Fleeting Targets.

During the course of the preliminary bombardment, opportunities will occasionally be presented of causing loss to fleeting targets (reinforcements, reliefs, working parties or troops driven from shelter by artillery fire). Certain batteries should, therefore, be held avail-able on the "zone call" system to engage any such targets located from the air. Arrangements should also be made to extend this system to ground observing stations; so that any observer, seeing a favourable target, can pass information quickly to a selected and suitable battery. There is no reason to retain such batteries solely for this purpose; they can carry out other tasks as well.

Accuracy of Fire.

The necessity for destroying definite points in the enemy's organised system of defence demands the greatest accuracy of artillery fire, particularly when the opposing lines are but a short distance apart. The importance of accuracy cannot be over-estimated, and must be constantly ensured by means of definite orders, rigorous fire control, and constant supervision. To this end it is essential to arrange for periodical pauses in the bombardment of each section of the bom-barded area, in order that firing may be checked on datum points, the detachments rested, the equipment carefully inspected and minor repairs effected. During these pauses, every endeavour should be made to take air photographs of the hostile area, for these will disclose beyond argument the accuracy of the fire brought to bear and will enable commanders to repeat or to modify their bombard-ment programme accordingly.

Cases will occur where effect on the enemy's front trenches can only be ensured at the cost of an occasional round into our own trenches. This is a matter of pure ballistics, beyond human influ-ence, and must be recognised as such by infantry commanders. The advisability of withdrawing infantry from their trenches during a bombardment must depend on the local conditions. If the trenches are good and the men keep down, they may be safer in the front trenches than they would be if crowded in support trenches which may be heavily shelled at times by the hostile artillery. If the distance between the opposing trenches is such that some rounds are likely to fall in or short of our trenches, then the trenches must be cleared for the requisite time. The only alternative is to place the "mean point of impact" of the artillery fire beyond the target. This is unsound, as it entails a much reduced chance of achieving the destruction required at a greatly increased cost of ammunition. In view of the consideration that a few of our own heavy shells dropped in a crowded trench, especially just prior to the assault, may prove disastrous to the moral of the attacking troops, it will almost always be advisable to clear our trenches for the sake of an effective fire. The enemy is not likely to rush them in any strength at such a time. It is the duty of the Artillery Commander to make these points clear to the General Officer Commanding; it is the latter's duty to decide. If trenches are to be cleared, it is impor-tant that ample notice should be given to the infantry; in order that they may have time to make the necessary arrangements for temporary evacuation, and for denying to the enemy any opportunity of coming forward out of his trenches to avoid the effects of artillery fire.

Forward Guns.

In some cases guns dug in, actually in or close to the front line trenches, may prove of great value for special purposes, such as for making a breach in the hostile parapets or for knocking out machine guns. Provided time is available, experience shows that field guns can be got into almost any position, and that their fire at such short ranges produces a very marked effect. The secret of success lies in the most careful attention to detail. Unless every possible precaution is taken, the gun and detachment may both be put out of action before they have effected their purpose. Although there is no doubt that their presence has a great moral effect, their use must not be overdone, and they should not open fire until just before the assault.

Advanced Batteries.

Batteries placed right forward to open fire at or after the time of assault are considered in para. 18, Section VI.

Character of the Bombardment.

The programme of bombardment must be so arranged as to keep the enemy in a state of uncertainty as to the time when the infantry attack will be launched. The approximate hour of assault should be settled early and not changed. It will then be possible to ensure that, as far as the artillery is concerned, the actual assault shall come as a surprise. The German is peculiarly accustomed to order and regularity, and so it is advantageous to accustom him daily at the proposed hour of assault to a regular routine to which he must conform under pain of suffering casualties. Then, when the real hour comes, there will be a very good chance of letting the infantry into the enemy's trenches by making some slight alteration in that routine.

False ("Chinese") attacks are generally carried out during the bombardment with the object of inducing the enemy to man his parapets and then subjecting him to an intense man-killing fire. The infantry, trench mortars, &c., should participate in these feints so as to give the greatest impression of reality.
The lifts for the attack should be practised during the bombard-ment. Officers must be detailed to watch all such shoots so that thin places in the barrage or inaccurate shooting may be rectified in time. For the former purpose balloon observation may also be employed with great advantage. Further, the results can be corro-borated by means of air photographs, and arrangements should be made to photograph each practice barrage. Besides watching our own barrages, steps should be taken to observe and record those put down by the enemy, as much valuable information may be gleaned from this source.

The Bombardment of Rearward Lines.

As already stated a vigorous and systematic artillery fire must be maintained over the enemy's back areas up to the limits of gun range, with the immediate objects of inflicting casualties, arresting movement and generally disorganising his supply and other services. This will entail the deliberate destruction of many selected points in the enemy's rearward lines of defence, hut does not constitute a regular bombardment.

The extent to which rearward lines must be bombarded depends on several factors. The ultimate object of the first day's attack, the range to the rearward lines, the number of guns available and the duration of the bombardment all directly affect this question. It will rarely be possible to effect any extensive damage to the enemy's third line, where such exists, owing to the factor of range which limits the number of guns that can reach the objective.

If the attack is to go through to as great a depth as possible, and if time allows, then certain points in the enemy's second line should be selected for destruction on the same principles as govern the artillery attack of the front system of defence. If, on the other hand, the attack has a limited objective, or if the attack of successive objectives, spread over several days, is contemplated, then there can be but little value in any extensive bombardment of the second line. It is not unusual to find that before the assault considerable anxiety is expressed as to the destruction done to the wire and trenches of the second line. The fighting subsequent to the assault, particularly the various barrages, will do much towards opening a way through the second line of defence. It is easy to exaggerate the resisting power of rearward defences and to press for its reduction. But the first essential is to ensure the infantry's passage over the enemy's front line system of defence, and to take any chances in this respect in favour of more distant systems is manifestly indefensible.

Duration of the Bombardment.

No definite guide can be laid down as to the ideal length of an artillery bombardment. The underlying factors are numerous and the daily results achieved carry great weight. Hitherto, the moral effect of the enemy's wire has involved organised wire-cutting which in reality means a prolonged bombardment. It is possible, as explained in paragraph 3, Section V., that wire-cutting in the future will be carried out much more rapidly. The time theoretically required to destroy definite objectives depends on their nature and extent, upon the number of fire units available, and on the facilities for observation. If fire is to be conducted deliberately and with careful observation, this period can be calculated with considerable accuracy. Shortening the period may increase the chances of surprise and may so give the enemy no opportunity of bringing up additional artillery. A long bombardment is calculated to reduce the enemy's moral by its insistence, a short one by its intensity. In all cases it is the duty of the Artillery Commander to watch closely the progress of the artillery preparation, making such modi-fications in the allotment of guns and ammunition as he may con-sider necessary.

The evidence of photographs, corroborated by the reports of patrols and special observers, is the surest guide to the extent of material damage effected. The effect of the fire should be continuously observed by selected artillery officers and aeroplane observers. "Photographs showing the progress of the work of demolition are taken daily when conditions are favourable, and issued to all Divisional Commanders concerned as well as to the Corps Commander; Divisional Commanders must satisfy themselves that all danger points in their zones are adequately dealt with, and they should bring to the notice of the Corps Commander any points which, in their opinion, require further treatment. In considering the state of the enemy's defences, as disclosed by photo-graphs, it must be remembered that considerable further effect will be achieved by the bombardment which remains to be carried out between the time that the last photograph is taken and zero hour on the day of attack; and also by the howitzer bombardment which lifts forward from trench to trench from zero hour onwards."*
[*See Section III., para. 3, of " Instructions for Training of Divisions for Offensive Action."]

VI. The Support of the Attack.

The General Mission of the Artillery.

Adequate artillery preparation will not alone ensure the success of an attack. The support of the infantry during the attack is at least as important, and in this phase the general mission of the artillery consists of :

Beating down all resistance to the advance, from either front or flanks.

Preventing the assembly and approach of counter-attacks of all sizes.

In a word the artillery must aim at overcoming the enemy's bat-teries, riflemen and machine guns that have not been destroyed during the preliminary bombardment.

Importance of Concealing the Hour of the Assault.

Every precaution must be taken to ensure that the actual assault should come as a surprise. It will probably be impossible to conceal from the enemy the intention of an attack on a large scale. If any indication of the actual hour of assault is afforded (as by an obvious change in the intensity or nature of artillery fire, bayonets showing over the trenches, advancing "tanks," &c., &c.) the enemy's in-fantry will be in instant readiness to man their parapets, the hostile artillery barrage may come down and the assault may possibly never start.*

If on the other hand no notice is given to the enemy, he will not know until too late exactly where his barrage is required.
[* See Section V. of "Instructions for tie Training of Divisions for Offensive Action."]

Barrages.

The barrage system has been lately developed. It must be re-membered that, while the following notes deal with the procedure that has recently been the most successful, it is only to be expected that the enemy will devise new methods to defeat our barrage fire. New methods on his part will call for immediate modifications in our artillery tactics.

Object of the Barrage.

The object of the artillery barrage is to prevent the enemy from manning his parapets and installing his machine guns in time to arrest the advance of our infantry. It has already been explained that permanent concrete emplacements for machine guns must be destroyed during the preliminary bombardment and that a daily searching of the ground with shrapnel fire is a helpful method of dealing with machine guns sited in shell holes and shallow positions in front of or behind the immediate objective. Machine guns kept in deep dug-outs, or even in deep shell holes if undercut, cannot be destroyed by these means; but on the other hand, a certain period of time is required to bring up and mount such guns. Though this period is not long, it is quite sufficient to enable the attacking infantry to deal with the situation if they are close up under the barrage. The barrage must, therefore, be sufficiently heavy to keep the enemy in his dug-outs and shelters as long as possible, and sufficiently accurate to allow the infantry to get so close to the trench attacked that, when the barrage lifts, they can cover the remaining distance before the enemy can prepare to receive them.

The Field Artillery Barrage.

To deal with the enemy's infantry and his variously sited machine guns the Field Artillery Barrage may consist of "creeping," "back" and "standing" barrages applied separately or simul-taneously.

The "standing" barrage opens on each objective when it is to be assaulted, with the object of forcing the enemy to take cover and of preventing him manning his defences before the infantry reach the position.

The "back" barrage meanwhile searches and sweeps all the ground in rear of the objective whence rifle or machine gun fire might be directed against the advancing infantry.

Whether in addition to these two barrages a "creeping" barrage will also be required depends on the distance to be traversed by the infantry from their "jumping off" place to their objective. If this distance is such that the infantry is not sufficiently protected by the fire of the "standing" barrage against any machine guns or riflemen that may still lurk in shell holes, then a "creeping barrage" should precede the advancing infantry, with its Mean Point of Impact at a distance of 200 yards or so in front of them, and move forward till it joins the "standing" barrage, when both barrages lift off together. It must, however, be remembered that the simultaneous employment of three barrages is to be avoided on principle, as it entails a maximum dispersion of effort on the part of the artillery available.

In the first assault, a "creeping" barrage will usually be unneces-sary, as the distance between the opposing trenches will, as a rule be such that the "standing" barrage will be all that is possible or necessary.
In later stages, when the enemy has been forced back into hastily dug trenches, the "standing" barrage may sometimes dispensed with in favour of the "creeping" barrage which can fill the dual role by dwelling for a certain time on each objective to be assaulted. In this case the object of the barrage is to allow the infantry to "follow close up to the barrage from the instant it commences, and then taking advantage of this 'dwell,' work up as close as possible to the objective, ready to rush it at the moment that the barrage lifts." In either case the one essential is that the infantry shall be able to move as close up to the barrage as is possible so that "the time which elapses between the barrage lifting and the infantry entering the trench may be less than that required by the enemy to man their parapets" and install their machine guns. Success or failure is a matter of a few seconds.*

The barrage will meanwhile approach the next objective, picking up the back barrage en route and being organised on a similar system to that arranged for the first objective.

Strength of Field Artillery Barrages.

The following figures may be taken as a general guide to the relative strengths of Field Artillery barrages:
One 18-pdr gun per 15 yards should provide adequate barrages of all natures.
An 18-pdr. "back" barrage does not require a large number of guns; about one-eighth of the total available should suffice.**
[* See Section III. para. 4. of " Instructions for the Training of Divisions for Offensive Action."]
[** Where both "creeping" and "standing" barrages have been employed it has been found that the latter has usually consisted of about one-third of the available guns, the "creeping" barrage of the rest, but the proportion must depend on the ground and on the dispositions of the enemy.]

The Organisation of the Barrage.

The barrage lines throughout the corps must be arranged by the G.O.C., R.A. Corps, in accordance with the Corps Commander's directions, after consultation with Divisional Commanders, and are best communicated to subordinate commanders in the form of a map showing all the lifts. No changes should be permitted once the bar-rages have been worked out and issued, except on a change of the general plan of attack.

It is laid down ("Instructions for the Training of Divisions for Offensive Action"issued by the General Staff, December, 1916 Section 135, page 62, para. 3 (i)), that the front or jumping-off trench must be as nearly parallel as possible to the enemy's front line so that the leading waves may jump off square to their objec-tive. This is of great importance to the placing of the barrage, as the first objective (the enemy's front trench) can thus be subjected to a barrage from the Heavy Artillery along its whole length, and then to an 18-pdr. barrage followed by a simultaneous assault by the infantry. Against subsequent objectives, however, it will often follow that the infantry cannot jump off from a parallel line, and in this case the barrage should swing so that it is parallel to the objective along its whole length before it finally lifts on to the objective. Occasionally it may be difficult to execute this "swing" of the barrage; in such cases the alternative method is to arrange for each small section of the barrage, as it reaches the trench line, to stop there until gradually the whole length of the barrage has been built up. In both cases the barrage ultimately lifts off simul-taneously; the fact that certain portions of the assaulting lines are kept waiting while the barrage either swings or is built up does not matter. A barrage that remains parallel to the jumping-off line does not keep the troops waiting in the open; but the infantry's arrival on the objective is not simultaneous and, wherever the trench bends, there is an open space between the barrage and the part of the trench occupied by our troops. This may contain the entrance to a dug-out, and it is quite possible that the enemy's machine gunners may receive warning and get their guns mounted in time (see Appendix II.).

Pace of the Barrage.*

"(i) The secret of a successful assault rests upon the assumption that the infantry conform their movements exactly to the timing of the barrage. The importance of this timing, therefore, cannot be over-estimated. If the lifts are too quick, the pace will be too fast and the infantry will fail to keep up with the barrage. Once this happens the whole advantage of the barrage will be lost, as the enemy will have time to man his parapet before the infantry reach it. The advance will then be brought to a standstill under close-range enemy rifle and machine-gun fire, while the barrage moves further and further away in accordance with the time table."

"If there is too long a pause between each lift, the pace will be too slow, and the rear waves will push on too fast and become mixed up with the leading waves, thereby forming a thicker line and increasing casualties, besides losing the driving power which a series of waves gives to the attack."

"(ii) It is impossible to lay down any definite ruling as to the best pace; it must be regulated entirely by local conditions." The great thing is not to go too fast. The pace must be such that the slowest man can easily keep close up under the barrage. 100 yards in 3 minutes is a good average pace over dry ground pitted with shell holes.

"The state of the weather, the extent to which the ground is cut up by shell fire, the length of the advance, the number of enemy trenches to be crossed, all affect the pace at which the infantry, and consequently the barrage, can move. In actual practice, the pace has varied from 75 yards a minute, when conditions were very favourable, to 15 yards a minute when they were very unfavourable."
"(iii) A uniform pace throughout the advance is unsound; at the commencement the pace of the barrage should be quicker, gradually slowing down towards the finish as the men become exhausted, in order to give them time to get close up to the barrage and to pull themselves together for the final rush."

"In the case of a long advance, it is advisable to keep the barrage on the objective for a double period, in order to make quite certain that the men are closed up and ready to rush the trench."

"Above all, it is essential that in the attack of a more or less intact system of defence the infantry should cross 'No Man's Land' as quickly as possible. To achieve this, it is of vital importance that the infantry should start off at zero time with absolute punctuality, for any delay at this moment may be disastrous."
[* See Section III, paras. 5, 6 & 7, of "Instructions for the Training of Divisions for Offensive Action."]

Time Tables.*

"The timing of the barrage is fixed, as part of the Corps Artillery plan, by the Corps Commander after consultation with Divisional Commanders, particular attention being paid to the points of junc-tion between Divisions to ensure that the barrages on each Divisional front overlap properly.
The timings worked out are then embodied in a programme or time table and issued to all concerned.

The duration of the barrage depends on the number of objectives to be gained.
Where there is only one objective, the barrage, after lifting off the objective, will continue to creep forward till it reaches a line about 300 yards beyond the objective. This distance is necessary to give room for outposts to be pushed out to cover the consolida-tion."

"The barrage then becomes stationary and gradually dies down, ceasing altogether as soon as the infantry report that they have secured the objective."
"When there is another objective, there will be a certain pause, previously arranged and laid down, to enable the troops detailed for the assault of the next objective to get into position; the barrage will then commence moving forward again in accordance with the time table."
[* See Section III, paras. 5, 6 & 7, of "Instructions for the Training of Divisions for Offensive Action."]

Control of the Barrage.*

" (i) The control of the barrage remains in the hands of the corps commander throughout the assault, but, in order that divisional commanders may be able to deal promptly with any situation which may arise on their front, they will be given a call on a certain number of batteries (18-pdr., 4.5-inch and 6-inch howitzer) from the commencement of the assault."

"All batteries thus detailed will have tasks allotted to them in accordance with Corps Orders and will carry them out, unless and until their assistance is demanded by the divisional commander concerned."

"The divisional commander will demand the assistance of these batteries through the commander of all the field artillery supporting his division. The latter officer will have his headquarters at Divisional Headquarters, if possible, and will be in direct communi-cation with all the field artillery groups under him and also with the G.O.C., R.A. Corps."

"(ii) To enable commanders of assaulting brigades to take immediate action in any situation which may arise, the Divisional Commander may delegate to the Brigadiers concerned the power to call direct on some of the batteries placed at his disposal."

"The Brigadier will call on these batteries through the commander of the field artillery directly supporting his Brigade. This latter officer will, whenever possible, establish his Headquarters in the immediate vicinity of the Infantry Brigade Headquarters, but where this is not possible he will maintain the closest touch with the Infantry Brigadier by means of a senior Artillery Liaison Officer."

"The governing factor as to which of these two methods should be followed is to a great extent a question of communications. Unforeseen situations will always arise necessitating the passage of orders and information between a Divisional C.R.A. and his Group Commanders. If the Headquarters of an Infantry Brigade is so placed that communication between an Artillery Group Commander at or near those Headquarters and his Divisional C.R.A. has a reasonable prospect of remaining continuously open, such is the best solution. If not, then the Artillery Group Commander is better represented by a responsible Liaison Officer."

"(iii) Except when minor operations by single battalions are being carried out, it will usually be unnecessary to give officers com-manding assaulting battalions the power to call on batteries, and consequently these officers will not require Artillery Liaison Officers."
[* See Section III, paras. 5, 6 & 7, of "Instructions for the Training of Divisions for Offensive Action."]

Rate of Fire and Depth of Lifts.

The rate of fire of 18-pdrs. should never exceed 4 rounds per gun per minute and this rate should only be maintained for short periods. The equipment will not stand more.

Field Artillery lifts should be approximately 100 yards at a time. Intermediate lifts must be arranged so that any trenches or works in front of the objective are included in one of the lifts, and so that the final lift brings the fire right on to the objective. Except in these cases lifts of less than 100 yards are disadvantageous, as time is lost in adjusting the sights, and experience both in the field and on the range shows that at average ranges a 100-yards lift every three minutes completely searches the whole ground.

Enfilade Fire.

Enfilade fire is of value in the support of an infantry assault not only on account of its great effect, but also because of the accuracy with which it can be used. If the guns placed in position for this purpose are anchored and carefully registered for line on the enemy's front trench when at extreme traverse, the fire can be moved forward slowly as the infantry assault; but their utility comes to an end as soon as the other limit of traverse is readied. Guns so placed can also be used to form a "cross-barrage," i.e., one formed by guns firing at right-angles to one another, which will ensure some fire from a flank on any route which is attempted through the barrage. Care must be taken in using enfilade fire in support of an attack that there shall be no risk of hitting any bodies of our own infantry on the flank of or beyond those which the guns are immediately supporting.

Ammunition for the Field Artillery Barrage.

The barrage has two main properties:

a. It is a man-killing agent.
b. It acts as a screen to cover the movements of the infantry from view.

Therefore shrapnel (with a long corrector) presents distinct advantages for use in a "creeping" barrage under which the infantry has to advance, owing to the high proportion of possible man-killing missiles released by the burst of the shell and to the smoke cloud given off. If a large proportion of H.E. shell is employed, the covering screen will be too thin and the enemy will be able to bring aimed machine-gun fire to bear through the barrage from positions in rear. H.E. shell may, however, prove very valuable to cover attacks on woods and villages.

It is possible that the future may bring about considerable modi-fications in the method of carrying out barrages in view of the introduction of smoke shell. The use of H.E. shell for the "creeping" barrage may be capable of increase if preceded by a smoke barrage to form the necessary screen; or a mixed shrapnel and smoke barrage may conceivably be found useful, either of these methods releasing l8-pdrs. for the back barrage. H.E. and smoke shell, again, may prove of great use in this latter form of barrage. The employment of smoke shell is, however, still in its infancy, and the above possibilities are only to be regarded as indications of the direction in which artillery thought may ultimately turn.

The Howitzer Bombardment.*

At the moment of assault the enemy's artillery is a target of vital importance, and an adequate number of batteries must be employed to reduce the enemy's guns to comparative impotence. All howitzers not engaged in counter-battery work should begin an intense bombardment of the enemy's trenches, working up lanes in the same manner as the Field Artillery barrage. It depends upon the ground whether this bombardment moves forward just in front of the Field Artillery barrage, or whether it dwells on commanding points in rear within machine-gun range, thus increasing the strength of the back barrage. The moral effect of the former procedure is very great.** In either case this bombardment ultimately works forward well beyond the objective and then remains stationary on trenches, hollow roads, woods, villages, &c., where the enemy might assemble for a counter-attack. The effect of this bombardment can be increased if indirect machine-gun fire is brought to bear simul-taneously on the areas which are being bombarded, with a view to dealing with any of the enemy who attempt to escape the bombard-ment by leaving their trenches, &c.
[* See Section III, para. 4 (ii) of " Instructions for the Training of Divisions for Offensive Action."]
[** A mixed barrage, that is a. barrage of field and heavy artillery combined, has been found very efficacious as covering fire in the attack of a wood.]

Consolidation and Counter-attacks.

The artillery plan must include arrangements necessary to ensure the protection of the infantry after their ultimate objectives have been gained.
At every pause of any considerable length care must be taken that trenches, works, and approaches on the immediate flanks of the general infantry line, as well as areas suitable for the assembly of counter-attacking troops are kept under fire. The extreme flanks, where they bend back to the original line of departure, present an opportunity to the enemy unless they are rendered unapproachable by fire.

A final or "protective" barrage must be maintained beyond the ultimate objective as long as it is required by the infantry (see para. 9).

The rate of fire can gradually slacken, and medium and heavy howitzers need not ordinarily be used after the first hour unless called for; but any attempt to economise ammunition at this period may lead to the undoing of the whole attack. The principles of crushing hostile counter-attacks must be thoroughly understood. It is a critical period for the infantry when they first become exposed to the hostile artillery firing in preparation of the main counter-attack, which will not, of course, ordinarily develop for some hours. The artillery, however good the counter-battery work, cannot prevent the infantry being shelled at this period when distant or even new hostile batteries will probably have come into action and when every hostile gun that can fire will do so regardless of losses. But the artillery, working in conjunction with the Air Service, should be able to prevent the enemy from assembling for a counter-attack. That must be the chief aim of the artillery. If, however, the enemy does manage to launch a counter-attack, then the guns must bring it to a stop.

Directly the enemy's artillery preparation begins, our artillery must fire in counter-preparation. The enemy's batteries must be engaged; a destructive fire directed on his foremost trenches, works, and likely places of assembly; and all approaches and roads, as well as billets, dumps, &c., must be shelled.
Fire in counter-preparation must be conducted with an energy and intensity superior to that of the enemy, and last for as long a time. At the first sign of an infantry attack, a strong protective barrage must be at once placed close in front of the infantry through-out the length of the line attacked.

Zone Calls.

(See " Co-operation of Aircraft with Artillery," 1916, paras. 22-25.) The Zone Call system has proved its value in battle. Batteries should be specially detailed to answer zone calls and deliver an overwhelming fire on every target notified by this means. The material results are often great, but the moral effect is greater still. The hostile infantry feel that if they are seen moving even in a trench by an airman, a heavy fire is quickly brought to bear on them, and their moral suffers accordingly.

Zone calls from the air have proved particularly useful while the infantry are consolidating under cover of the protective barrage. Targets presented by bombing parties preparing to attack our "stops," local reserves leaving their dug-outs and larger bodies further to the rear forming up for counter-attack, can be quickly and effectively engaged by this means. It is for these reasons that, when arranging barrages, some batteries should always be earmarked to receive and act upon these calls, most particularly at that period when the final objective has been gained.

Information and Communication.*

The chief trouble of the artillery is lack of information during the first hours of the battle, for infantry find it extremely difficult to report their exact positions in a shelled country whence all land-marks have disappeared.
Reliable communications and constant touch between artillery and infantry commanders are essential to successful co-operation, but difficult to achieve in the actual course of a battle. Every possible means must be considered and utilised where suitable; telephone, signalling apparatus, wireless sets, rockets, flares, light pistols, carrier pigeons, messenger dogs, and, above all, runners. For the first hour or so after the assault, until communications can be well established, the difficulty of maintaining communication between the two arms is felt, and this difficulty increases when the artillery make their first advance.

Lights.During these periods communication will generally be restricted by force of circumstances to calls for barrage fire by means of light signal rockets or light pistols. All such signals from the front line must be repeated back by intermediate stations, if neces-sary as far as the batteries themselves.

Visual Signalling often proves a valuable adjunct for main-taining communication in difficult positions and can be used in combination with telephones and runners. The following system has been found useful: 

DIAGRAM

"Coloured flags, carried by one or two men in each platoon, can be used to indicate to the artillery the line gained by the leading infantry. These flags must not be stuck in the ground and will mean nothing unless they are waved; the poles should be short and blunted at the end. A combination of black and yellow on a flag about 18 inches square is the easiest to observe."
"Flares.The position of the leading infantry has been success-fully indicated to aeroplane observers (and so transmitted to the artillery) by the lighting of flares at certain pre-arranged times or at an agreed signal from the aeroplane."*

Special Artillery Observing Stations have already been mentioned as a means of great value for watching the progress of the infantry. (see para. 5, § IV.).

Artillery Command Posts have also been discussed so far as regards their position (see para. 6, § IV.). The work of the heavy artillery is so intimately connected with that of the field artillery that direct communication should always be established between Divisional Artillery Commanders and Commanders of either Corps Heavy Artillery or of Heavy Artillery Groups, according to the artillery plan, so that in the stages subsequent to the assault no time may be lost in rapid inter-communication and consequent action when required.

Battery Commanders must be where they can best see the general situation. Once the attack has been launched this changes so rapidly that there is often no time to receive orders from higher commanders, and battery commanders must be prepared to act instantaneously on their own initiative, of course informing their Brigade or Group Commander of the action taken.
[* See Section III, para. 8, of "Instructions for the Training of .Divisions for Offensive Action."]

The Artillery Advance.

Artillery on the move is for the time being useless and the advance, particularly that of heavy artillery, is a lengthy process unless it has been worked out in every detail.

Continuity of artillery in action can only be obtained if its advance is made by echelons and practically without interruption.

The next positions must be decided, at least approximately, for each brigade or group and the time when it will probably have to move must be considered.
In order to assist the necessary continuity of artillery fire, it will often be advantageous to place certain batteries in action close to the front trenches, with the proviso that they do not open fire before the attack takes place. Such positions must be carefully concealed.

Additional positions in this area may be earmarked, or even pre-pared, for other artillery and should be capable of early occupation. Even if the emplacements cannot be dug, it should be possible to do much towards preparing the artillery boards, communications and approaches. Here again camouflage must be freely employed.

The provisional selection of positions between the trenches or beyond the enemy's front line must be based upon study of the map and air photographs, assisted by personal reconnaissance from observing stations.
For all positions that are not constructed before the attack (see Appendix III.), the Artillery Commander and the General Staff concerned must consider the provision of labour. The mass of artillery will have been at work almost unceasingly since the open-ing of the bombardment and, if their fire is to be re-opened after movement with minimum delay, every endeavour should be made to assist the batteries with personnel for labour.

The amount of artillery that is called upon to advance early will of course vary directly as the measure of success attained; but, whatever the number of batteries involved, support of the infantry remains the foremost consideration. As the infantry push well ahead, the first step in their distant support is assured by means of those batteries which have been placed right forward. The first batteries to move will be certain field batteries and a proportion of the more mobile heavy artillery units (60-pdrs. and 6-inch howitzers) which must have been earmarked for this duty. If it is possible to relieve these batteries of any participation in the first phases of the battle, their subsequent movement can be made at short notice. Their routes must have been ordered in advance and improved where necessary. Beyond this again it will naturally follow as a principle that the most retired batteries must be moved forward early, before the battle line progresses beyond the limits of their range and while the more advanced batteries have sufficient range left to cover their movement without unduly weakening the artillery support.

While field artillery is in motion, an increased responsibility will be thrown on the heavy artillery as regards the direct support of the infantry and this also must be arranged for.

Careful organisation is necessary for the proper command of guns pushed forward battery by battery, particularly in the case of heavy batteries. These latter must either be attached to divisions or, if it is desired to retain them under Corps control, may be organised to form a special Heavy Artillery Group under a selected commander.

Appendix I.

G.O.C. R.A. ARMY.

Staff Officer (graded as D.A.A.G.)

Staff Captain

Reconnaissance Officer (graded as Staff Captain)

G.O.C. R.A. CORPS.

Staff Captain

Staff Officer (graded as D.A.A.G.)

Reconnaissance Officer (graded as Staff Captain)

B.-G. C.H.A.

Brigade Major

Staff Captain

Reconnaissance Officer (graded as Staff Captain)

Counter-Battery Staff Officer

Orderly Officer

C.R.A. DIVISION.

Brigade Major

Staff Captain

Reconnaissance Officer (graded as Staff Lieut. 1st Class)

Appendix IV.
Ammunition in Relation to Tasks

The following figures may be taken as a rough guide to the amount of ammunition required for the tasks specified under normal conditions and for medium ranges: 

Task

Weapon

No. of Rounds

1. Wire-cutting

18-pdr.

7_ (Shrapnel) + 5% H.E. per yard of front, for a depth of wire
not exceeding the 50% zone of the gun at the range.